1. Field of the Invention
The present invention relates generally to connectors for coupling cables to terminals, or to one another, etc., and methods for assembling and using the same. More specifically, the invention relates to connectors for coaxial cables and related methods, wherein the connector can provide an environmental sealing role.
2. Description of Related Art
There are many applications in which it is advantageous to connect a coaxial cable to a terminal, another coaxial cable, and the like. Coaxial cable F-connectors, for example, are often used to terminate coaxial cables, such as a drop cable in a cable television system. Such coaxial cables typically include a center or inner conductor surrounded by a dielectric or core, in turn surrounded by an outer conductor and/or braid, which in turn is surrounded by an outer insulator referred to as a jacket. The F-connector is secured over the prepared end of the jacketed coaxial cable, allowing the end of the coaxial cable to be threadedly connected with a threaded terminal block.
A problem with prior coaxial cable designs, particularly in outdoor applications, has involved unwanted infiltration of moisture at the connector and into the interior of the cable. This can impair performance, for example, by leading to corrosion, affecting the electrical characteristics within the cable, increasing contact resistance, reducing signal strength, causing excessive RF leakage from the connector, etc. Those skilled in the art have made various efforts to form a seal between the connector and the jacket of the coaxial cable to preclude such moisture ingress. Connectors are known in the cable television industry wherein special sealing compounds and/or o-ring seals are included in an effort to form leakproof seals.
Crimp style F-connectors are known, for example, wherein a crimp sleeve is included as part of the connector body. A special radial crimping tool, typically having jaws that form a hexagon, is used to radially crimp the crimp sleeve around the outer jacket of the coaxial cable to secure such a crimp style F-connector over the prepared end of the coaxial cable. Examples of such crimp connectors are disclosed in U.S. Pat. No. 4,400,050 to Hayward, assigned to Gilbert Engineering Co., Inc.; and U.S. Pat. No. 4,990,106 to Szegda. U.S. Pat. No. 4,755,152 to Elliot et al. discloses a crimp connector incorporating a gel or other movable sealing material within a cavity of the connector to form a seal between the jacket of the coaxial cable and the interior of the F-connector.
Still another form of F-connector is known wherein an annular compression sleeve is used to secure the F-connector over the prepared end of the cable. Rather than crimping a crimp sleeve radially toward the jacket of the coaxial cable, these F-connectors employ a plastic annular compression sleeve that is initially attached to the F-connector, but which is detached therefrom prior to installation of the F-connector. The compression sleeve includes an inner bore for allowing the end of the coaxial cable to be passed through such compression sleeve prior to installation of the F-connector. The F-connector itself is then inserted over the prepared end of the coaxial cable. Next, the compression sleeve is compressed axially along the longitudinal axis of the connector into the body of the connector, simultaneously compressing the jacket of the coaxial cable between the compression sleeve and the tubular post of the connector. An example of such a compression sleeve F-connector is shown in U.S. Pat. No. 4,834,675 to Samchisen, which discloses a compression sleeve type F-connector known in the industry as “SNAP-N-SEAL,” commercially available from LRC (Thomas & Betts). A number of commercial tool manufacturers provide compression tools for axially compressing the compression sleeve into such connectors. The CablePrep division of Ben Hughes Communication Products Company of Chester, Conn., for example, sells such a hand-operated compression tool under the commercial designation “TERMINX.”
The aforementioned “SNAP-N-SEAL” compression connector requires substantial manipulation by an installer. The installer must detach the annular compression sleeve from the connector, slide the compression sleeve over the end of the coaxial cable, then install the connector, and finally compress the compression sleeve into the body of the connector. During assembly, the compression sleeve can easily become lost because of its typically small size and because it must be detachable from a mounting neck. In addition, such “SNAP-N-SEAL” connectors are significantly more expensive than conventional crimp style connectors.
Yet another radial compression-type F-connector is disclosed in U.S. Pat. No. 5,470,257 to Szegda. A tubular locking member protrudes axially into the open rear end of the outer collar or sleeve. The tubular locking member is displaceable axially within the outer collar between an open position accommodating insertion of the tubular post into the prepared end of the coaxial cable, and a clamped position fixing the end of the cable within the F-connector. An O-ring is mounted on the rear end of the tubular locking member to seal the connection between the tubular locking member and the outer collar as the tubular locking member is axially compressed. Such connectors have been sold in the past under the designation “CMP” by PPC Industries. The O-ring provided on the tubular locking member is exposed and unprotected prior to axial compression of the F-connector.
It is generally known in the coaxial cable field that collars or sleeves within a coaxial cable connector can be compressed inwardly against the outer surface of a coaxial cable to secure a coaxial cable connector thereto. For example, in U.S. Pat. No. 4,575,274 to Hayward and assigned to Gilbert Engineering Company Inc., a connector assembly for a signal transmission system is disclosed wherein a body portion threadably engages a nut portion. The nut portion includes an internal bore in which a ferrule is disposed, the ferrule having an internal bore through which the outer conductor of a coaxial cable is passed. As the nut portion is threaded over the body portion, the ferrule is wedged inwardly to constrict the inner diameter of the ferrule, thereby tightening the ferrule about the outer surface of the cable. In some situations, the connector shown in the Hayward '274 patent can not be installed quickly, as by a simple crimp or compression tool. Rather, the mating threads of such connector generally must be tightened, for example, using a pair of wrenches.
Known coaxial cable connectors typically require a number of components to secure the cable to the terminal, splice, etc., and attempting to do so in a way that a suitable environmental seal is obtained. The need for these various components results in added relative cost of the components themselves, as well as the costs associated with maintaining parts inventories, assembly time and effort, installation time and effort, etc.